🇬🇧 UK

Why does my tax refund look different from what I expected?

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GlobalPublished 6 October 2026 · Written by BuyMeWhiskey Editorial Team · How we check facts

A UK tax refund can differ from your estimate because HMRC calculates tax from your actual reported income, allowances, deductions and tax already paid. For 2026/27, the standard Personal Allowance is £12,570, but the final refund depends on your own tax calculation rather than a simple percentage of pay.

Next question: Is my tax correct for the 2026/27 tax year? →

Use your HMRC Personal Tax Account or P800 calculation to check the figures HMRC used before assuming a refund is wrong.

Check your Income Tax with HMRC

Run your own numbers: UK take-home pay calculator 2026/27.

Why can a tax rebate be different from an estimate?

A tax refund is the result of a tax calculation, not a standard rebate percentage. HMRC compares the tax that should have been due with the tax actually paid. The result can be a refund, an underpayment or no adjustment at all.

For the 2026/27 tax year, GOV.UK lists the standard Personal Allowance at £12,570. The allowance is the amount of income a person can generally receive before Income Tax is charged, but the actual tax bill also depends on the income bands, source of income and other circumstances.

What does a P800 tell you?

After HMRC calculates a year's PAYE Income Tax, it may send a tax calculation letter called a P800. GOV.UK says the P800 explains whether you are due a refund or need to pay more tax and tells you how to get or make the adjustment.

If the letter says you can claim online, HMRC currently says an online refund can be paid within five working days after the claim, while a cheque request can take six weeks. If HMRC says it will automatically send a cheque, the government says it should arrive within 14 days of the date on the letter.

What should you check when the numbers look wrong?

Employment income and pension income reported to HMRC.
Your tax code and whether it changed during the year.
The amount of Income Tax already deducted.
Any taxable benefits or other income included.
Whether you used Self Assessment for part of the year.

GOV.UK's tax-checking service lets you review how much Income Tax HMRC says you paid for the previous tax year. If you used Self Assessment, the process is different and the P800 service may not cover all of your tax.

Why the tax bands matter

For England, Wales and Northern Ireland in 2026/27, GOV.UK lists a 20% basic rate on taxable income up to £37,700 after allowances, a 40% higher rate from £37,701 to £125,140, and a 45% additional rate above £125,140. Scotland has different bands and rates.

That means someone cannot reliably estimate a refund by taking one flat rate of tax from total gross pay. Different portions of taxable income can fall into different bands, and allowances can change the calculation.

What if HMRC's calculation contains an error?

GOV.UK says that if you think the amounts used in the calculation are wrong, you should contact HMRC and explain which amounts are incorrect and what they should be. If HMRC agrees, it will issue a new calculation.

Do not treat an unexpected refund as proof that HMRC is wrong. First compare the P800 with your payslips, pension records and tax-code notices. If the figures do not reconcile, ask HMRC to explain them before spending the refund.

What about tax already paid through PAYE?

PAYE withholding is an estimate collected through payroll. It does not guarantee that the final annual tax bill will equal the total tax withheld. A job change, multiple employments, changing benefits, pension income or a tax-code correction can all change the final result.

For a clean check, add the tax deducted on your payslips, compare it with the annual figures HMRC holds and then reconcile any difference to the P800.

Could a tax-refund message be a scam?

Yes. A genuine HMRC calculation and a scam email are separate things. Do not enter bank details through an unexpected link just because the message promises a refund. Use GOV.UK or your HMRC account directly and independently check the address before providing information.

Worked example

Illustrative PAYE calculation: Assume a taxpayer in England has gross employment income of £32,570 in 2026/27 and, for this simplified example, has the standard £12,570 Personal Allowance with no other taxable income or adjustments. The simplified taxable income would be £20,000.

Math: £32,570 - £12,570 = £20,000. At the basic Income Tax rate of 20%, the simplified tax would be £4,000.

Math: £20,000 × 20% = £4,000.

If payroll had deducted an illustrative £4,250 during the year, the simplified overpayment would be £250.

Math: £4,250 - £4,000 = £250.

This is only an illustrative calculation. Real PAYE outcomes can include other income, benefits, pension deductions, tax-code changes and Scottish rates. Use HMRC's actual figures rather than assuming an estimated refund is the final amount.

Why is my HMRC tax refund smaller than expected?#

HMRC's final calculation may include income or tax information that was missing from your estimate. A refund is based on the tax actually due compared with tax already paid, not on a fixed rebate rate. Compare the P800 with your payslips and tax-code history before deciding that the refund is wrong.

What is the Personal Allowance for 2026/27?#

The standard UK Personal Allowance for the 2026/27 tax year is £12,570. GOV.UK says it starts to be reduced once adjusted net income is above £100,000, falling by £1 for every £2 above that level until it reaches zero.

How long does an HMRC refund take?#

For a P800 that says you can claim online, GOV.UK currently says the money will be sent within five working days after the online claim. A cheque requested online can take six weeks. If HMRC says it will automatically send a cheque, GOV.UK says it should arrive within 14 days of the letter date.

Can I check how much tax HMRC says I paid?#

Yes. GOV.UK provides a service for checking the Income Tax HMRC says you paid for the previous tax year, with access through your online tax account. The service does not cover every Self Assessment situation, so check which route applies to your circumstances.

What if my P800 is wrong?#

GOV.UK says to contact HMRC and identify exactly which figures you think are wrong and what they should be. HMRC can issue a new calculation if it agrees. Keep your payslips, pension records and tax-code notices so you can show where the discrepancy comes from.

Can a tax refund email be fake even if I am expecting money?#

Yes. Treat the email and the tax calculation as separate things. Use GOV.UK or your HMRC account directly rather than clicking an unexpected refund link. Do not provide bank details or login codes simply because a message uses HMRC branding.

Keep reading

Next question →Is my tax correct for the 2026/27 tax year?

Sources

Figures were checked against these sources before publication. If a rule changes, we update the page and show the new date.

General information, not personal financial advice. Rules depend on your circumstances; check the official source or speak to a regulated adviser before acting.